<?php

namespace App\Service;

use Exception;

class Image
{

    // 来自于 think-image

    /* 缩略图相关常量定义 */
    const THUMB_SCALING   = 1; //常量，标识缩略图等比例缩放类型
    const THUMB_FILLED    = 2; //常量，标识缩略图缩放后填充类型
    const THUMB_CENTER    = 3; //常量，标识缩略图居中裁剪类型
    const THUMB_NORTHWEST = 4; //常量，标识缩略图左上角裁剪类型
    const THUMB_SOUTHEAST = 5; //常量，标识缩略图右下角裁剪类型
    const THUMB_FIXED     = 6; //常量，标识缩略图固定尺寸缩放类型
    /* 水印相关常量定义 */
    const WATER_NORTHWEST = 1; //常量，标识左上角水印
    const WATER_NORTH     = 2; //常量，标识上居中水印
    const WATER_NORTHEAST = 3; //常量，标识右上角水印
    const WATER_WEST      = 4; //常量，标识左居中水印
    const WATER_CENTER    = 5; //常量，标识居中水印
    const WATER_EAST      = 6; //常量，标识右居中水印
    const WATER_SOUTHWEST = 7; //常量，标识左下角水印
    const WATER_SOUTH     = 8; //常量，标识下居中水印
    const WATER_SOUTHEAST = 9; //常量，标识右下角水印

    /**
     * 图像资源对象
     *
     * @var resource
     */
    protected $im;


    /**
     * 图像信息，包括 width, height, type, mime, size
     *
     * @var array
     */
    protected $info;

    protected function __construct(\SplFileInfo $file)
    {
        //获取图像信息
        $info = @getimagesize($file->getPathname());

        //检测图像合法性
        if(false === $info || (IMAGETYPE_GIF === $info[2] && empty($info['bits']))){
            throw new Exception('Illegal image file');
        }

        //设置图像信息
        $this->info = [
            'width'  => $info[0],
            'height' => $info[1],
            'type'   => image_type_to_extension($info[2], false),
            'mime'   => $info['mime'],
        ];

        //打开图像
        if('gif' == $this->info['type']){
            //$this->gif = new Gif($file->getPathname());
            //$this->im  = @imagecreatefromstring($this->gif->image());
        } else{
            $fun      = "imagecreatefrom{$this->info['type']}";
            $this->im = @$fun($file->getPathname());
        }

        if(empty($this->im)){
            throw new Exception('Failed to create image resources!');
        }

    }

    /**
     * 打开一个图片文件
     * @param \SplFileInfo|string $file
     * @return Image
     */
    public static function open($file)
    {
        if(is_string($file)){
            $file = new \SplFileInfo($file);
        }
        if(!$file->isFile()){
            throw new Exception('image file not exist');
        }

        return new self($file);
    }

    /**
     * 保存图像
     * @param string $pathname 图像保存路径名称
     * @param null|string $type 图像类型
     * @return \SplFileInfo
     */
    public function save($pathname, $type = null)
    {
        //自动获取图像类型
        if(is_null($type)){
            $type = $this->info['type'];
        } else{
            $type = strtolower($type);
        }
        //JPEG图像设置隔行扫描
        if('jpeg' == $type || 'jpg' == $type){
            $type = 'jpeg';
            imageinterlace($this->im, 1);
        }
        //保存图像
        if('gif' == $type){
            //$this->gif->save($pathname);
        } else{
            $fun = "image{$type}";
            $fun($this->im, $pathname);
        }

        return $this;
    }

    /**
     * 返回图像宽度
     * @return int 图像宽度
     */
    public function width()
    {
        return (int)$this->info['width'];
    }

    /**
     * 返回图像高度
     * @return int 图像高度
     */
    public function height()
    {
        return (int)$this->info['height'];
    }

    /**
     * 返回图像类型
     * @return string 图像类型
     */
    public function type()
    {
        return $this->info['type'];
    }

    /**
     * 返回图像MIME类型
     * @return string 图像MIME类型
     */
    public function mime()
    {
        return $this->info['mime'];
    }

    /**
     * 返回图像尺寸数组 0 - 图像宽度，1 - 图像高度
     * @return array 图像尺寸
     */
    public function size()
    {
        return [(int)$this->info['width'], (int)$this->info['height']];
    }

    /**
     * 裁剪图像
     *
     * @param integer $w 裁剪区域宽度
     * @param integer $h 裁剪区域高度
     * @param integer $x 裁剪区域x坐标
     * @param integer $y 裁剪区域y坐标
     * @param integer $width 图像保存宽度
     * @param integer $height 图像保存高度
     * @param boolean $is_alpha 保证以前的透明背景
     *
     * @return $this
     */
    public function crop($w, $h, $x = 0, $y = 0, $width = null, $height = null, $is_alpha = true)
    {
        //设置保存尺寸
        empty($width) && $width = $w;
        empty($height) && $height = $h;


        //创建新图像
        $img = imagecreatetruecolor($width, $height);
        imagesavealpha($img, true); //这里很重要 意思是不要丢了$sourePic图像的透明色
        // 调整默认颜色
        if(true === $is_alpha){
            $color = imagecolorallocatealpha($img, 255, 255, 255, 127);
        } else{
            $color = imagecolorallocate($img, 255, 255, 255);
        }
        imagefill($img, 0, 0, $color);
        //裁剪
        imagecopyresampled($img, $this->im, 0, 0, $x, $y, $width, $height, $w, $h);
        imagedestroy($this->im); //销毁原图
        //设置新图像
        $this->im = $img;

        $this->info['width']  = $width;
        $this->info['height'] = $height;

        return $this;
    }

    /**
     * 生成缩略图
     *
     * @param integer $width 缩略图最大宽度
     * @param integer $height 缩略图最大高度
     * @param int $type 缩略图裁剪类型
     * @param boolean $is_alpha 保证以前的透明背景
     *
     * @return $this
     */
    public function thumb($width, $height, $type = self::THUMB_SCALING, $is_alpha = true)
    {
        //原图宽度和高度
        $w = $this->info['width'];
        $h = $this->info['height'];
        /* 计算缩略图生成的必要参数 */
        switch($type){
            /* 等比例缩放 */
            case self::THUMB_SCALING:
                //原图尺寸小于缩略图尺寸则不进行缩略
                if($w < $width && $h < $height){
                    return false;
                }
                //计算缩放比例
                $scale = min($width / $w, $height / $h);
                //设置缩略图的坐标及宽度和高度
                $x      = $y = 0;
                $width  = $w * $scale;
                $height = $h * $scale;
                break;
            /* 居中裁剪 */
            case self::THUMB_CENTER:
                //计算缩放比例
                $scale = max($width / $w, $height / $h);
                //设置缩略图的坐标及宽度和高度
                $w = $width / $scale;
                $h = $height / $scale;
                $x = ($this->info['width'] - $w) / 2;
                $y = ($this->info['height'] - $h) / 2;
                break;
            /* 左上角裁剪 */
            case self::THUMB_NORTHWEST:
                //计算缩放比例
                $scale = max($width / $w, $height / $h);
                //设置缩略图的坐标及宽度和高度
                $x = $y = 0;
                $w = $width / $scale;
                $h = $height / $scale;
                break;
            /* 右下角裁剪 */
            case self::THUMB_SOUTHEAST:
                //计算缩放比例
                $scale = max($width / $w, $height / $h);
                //设置缩略图的坐标及宽度和高度
                $w = $width / $scale;
                $h = $height / $scale;
                $x = $this->info['width'] - $w;
                $y = $this->info['height'] - $h;
                break;
            /* 填充 */
            case self::THUMB_FILLED:
                //计算缩放比例
                if($w < $width && $h < $height){
                    $scale = 1;
                } else{
                    $scale = min($width / $w, $height / $h);
                }
                //设置缩略图的坐标及宽度和高度
                $neww = $w * $scale;
                $newh = $h * $scale;
                $x    = $this->info['width'] - $w;
                $y    = $this->info['height'] - $h;
                $posx = ($width - $w * $scale) / 2;
                $posy = ($height - $h * $scale) / 2;

                //创建新图像
                $img = imagecreatetruecolor($width, $height);
                imagesavealpha($img, true); //这里很重要 意思是不要丢了$sourePic图像的透明色
                // 调整默认颜色
                if(true === $is_alpha){
                    $color = imagecolorallocatealpha($img, 255, 255, 255, 127);
                } else{
                    $color = imagecolorallocate($img, 255, 255, 255);
                }
                imagefill($img, 0, 0, $color);
                //裁剪
                imagecopyresampled($img, $this->im, $posx, $posy, $x, $y, $neww, $newh, $w, $h);
                imagedestroy($this->im); //销毁原图
                $this->im = $img;

                $this->info['width']  = $width;
                $this->info['height'] = $height;

                return $this;
            /* 固定 */
            case self::THUMB_FIXED:
                $x = $y = 0;
                break;
            default:
                throw new Exception('不支持的缩略图裁剪类型');
        }

        /* 裁剪图像 */
        $this->crop($w, $h, $x, $y, $width, $height, $is_alpha);

        return $this;
    }


    /**
     * 添加水印
     *
     * @param string $source 水印图片路径
     * @param int $locate 水印位置
     * @param boolean $is_alpha 保证以前的透明背景
     * @return $this
     */
    public function water($source, $locate = self::WATER_SOUTHEAST, $is_alpha = true)
    {
        if(!is_file($source)){
            throw new Exception('水印图像不存在');
        }
        //获取水印图像信息
        $info = getimagesize($source);
        if(false === $info || (IMAGETYPE_GIF === $info[2] && empty($info['bits']))){
            throw new Exception('非法水印文件');
        }
        //创建水印图像资源
        $fun   = 'imagecreatefrom'.image_type_to_extension($info[2], false);
        $water = $fun($source);
        //设定水印图像的混色模式
        imagealphablending($water, true);
        /* 设定水印位置 */
        switch($locate){
            /* 右下角水印 */
            case self::WATER_SOUTHEAST:
                $x = $this->info['width'] - $info[0];
                $y = $this->info['height'] - $info[1];
                break;
            /* 左下角水印 */
            case self::WATER_SOUTHWEST:
                $x = 0;
                $y = $this->info['height'] - $info[1];
                break;
            /* 左上角水印 */
            case self::WATER_NORTHWEST:
                $x = $y = 0;
                break;
            /* 右上角水印 */
            case self::WATER_NORTHEAST:
                $x = $this->info['width'] - $info[0];
                $y = 0;
                break;
            /* 居中水印 */
            case self::WATER_CENTER:
                $x = ($this->info['width'] - $info[0]) / 2;
                $y = ($this->info['height'] - $info[1]) / 2;
                break;
            /* 下居中水印 */
            case self::WATER_SOUTH:
                $x = ($this->info['width'] - $info[0]) / 2;
                $y = $this->info['height'] - $info[1];
                break;
            /* 右居中水印 */
            case self::WATER_EAST:
                $x = $this->info['width'] - $info[0];
                $y = ($this->info['height'] - $info[1]) / 2;
                break;
            /* 上居中水印 */
            case self::WATER_NORTH:
                $x = ($this->info['width'] - $info[0]) / 2;
                $y = 0;
                break;
            /* 左居中水印 */
            case self::WATER_WEST:
                $x = 0;
                $y = ($this->info['height'] - $info[1]) / 2;
                break;
            default:
                /* 自定义水印坐标 */
                if(is_array($locate)){
                    list($x, $y) = $locate;
                } else{
                    throw new Exception('不支持的水印位置类型');
                }
        }

        //添加水印
        $src = imagecreatetruecolor($info[0], $info[1]);
        imagesavealpha($src, true); //这里很重要 意思是不要丢了$sourePic图像的透明色
        // 调整默认颜色
        if(true === $is_alpha){
            $color = imagecolorallocatealpha($src, 255, 255, 255, 127);
        } else{
            $color = imagecolorallocate($src, 255, 255, 255);
        }

        // 调整默认颜色
        imagefill($src, 0, 0, $color);
        imagecopy($src, $this->im, 0, 0, $x, $y, $info[0], $info[1]);
        imagecopy($src, $water, 0, 0, 0, 0, $info[0], $info[1]);
        imagecopymerge($this->im, $src, $x, $y, 0, 0, $info[0], $info[1], 100);
        //销毁零时图片资源
        imagedestroy($src);

        //销毁水印资源
        imagedestroy($water);

        return $this;
    }

    /**
     * 图像添加文字
     *
     * @param string $text 添加的文字
     * @param string $font 字体路径
     * @param integer $size 字号
     * @param string $color 文字颜色
     * @param int $locate 文字写入位置
     * @param integer $offset 文字相对当前位置的偏移量
     * @param integer $angle 文字倾斜角度
     *
     * @return $this
     * @throws Exception
     */
    public function text(
        $text,
        $font,
        $size,
        $color = '#00000000',
        $locate = self::WATER_SOUTHEAST,
        $offset = 0,
        $angle = 0
    ) {

        if(!is_file($font)){
            throw new Exception("不存在的字体文件：{$font}");
        }
        //获取文字信息
        $info = imagettfbbox($size, $angle, $font, $text);
        $minx = min($info[0], $info[2], $info[4], $info[6]);
        $maxx = max($info[0], $info[2], $info[4], $info[6]);
        $miny = min($info[1], $info[3], $info[5], $info[7]);
        $maxy = max($info[1], $info[3], $info[5], $info[7]);
        /* 计算文字初始坐标和尺寸 */
        $x = $minx;
        $y = abs($miny);
        $w = $maxx - $minx;
        $h = $maxy - $miny;
        /* 设定文字位置 */
        switch($locate){
            /* 右下角文字 */
            case self::WATER_SOUTHEAST:
                $x += $this->info['width'] - $w;
                $y += $this->info['height'] - $h;
                break;
            /* 左下角文字 */
            case self::WATER_SOUTHWEST:
                $y += $this->info['height'] - $h;
                break;
            /* 左上角文字 */
            case self::WATER_NORTHWEST:
                // 起始坐标即为左上角坐标，无需调整
                break;
            /* 右上角文字 */
            case self::WATER_NORTHEAST:
                $x += $this->info['width'] - $w;
                break;
            /* 居中文字 */
            case self::WATER_CENTER:
                $x += ($this->info['width'] - $w) / 2;
                $y += ($this->info['height'] - $h) / 2;
                break;
            /* 下居中文字 */
            case self::WATER_SOUTH:
                $x += ($this->info['width'] - $w) / 2;
                $y += $this->info['height'] - $h;
                break;
            /* 右居中文字 */
            case self::WATER_EAST:
                $x += $this->info['width'] - $w;
                $y += ($this->info['height'] - $h) / 2;
                break;
            /* 上居中文字 */
            case self::WATER_NORTH:
                $x += ($this->info['width'] - $w) / 2;
                break;
            /* 左居中文字 */
            case self::WATER_WEST:
                $y += ($this->info['height'] - $h) / 2;
                break;
            default:
                /* 自定义文字坐标 */
                if(is_array($locate)){
                    list($posx, $posy) = $locate;
                    $x += $posx;
                    $y += $posy;
                } else{
                    throw new Exception('不支持的文字位置类型');
                }
        }
        /* 设置偏移量 */
        if(is_array($offset)){
            $offset = array_map('intval', $offset);
            list($ox, $oy) = $offset;
        } else{
            $offset = intval($offset);
            $ox     = $oy = $offset;
        }
        /* 设置颜色 */
        if(is_string($color) && 0 === strpos($color, '#')){
            $color = str_split(substr($color, 1), 2);
            $color = array_map('hexdec', $color);
            if(empty($color[3]) || $color[3] > 127){
                $color[3] = 0;
            }
        } elseif(!is_array($color)){
            throw new Exception('错误的颜色值');
        }

        /* 写入文字 */
        $col = imagecolorallocatealpha($this->im, $color[0], $color[1], $color[2], $color[3]);
        imagettftext($this->im, $size, $angle, $x + $ox, $y + $oy, $col, $font, $text);

        return $this;
    }


    /**
     * 析构方法，用于销毁图像资源
     */
    public function __destruct()
    {
        empty($this->im) || imagedestroy($this->im);
    }

}
